Conventionally, a window module is used for closing a window opening such as a sunroof opening formed in a vehicle. A window module comprises a window panel made of a sheet of glass or plastic and a plastic molding attached to the peripheral part of the window panel. The molding is made of thermoplastic resin, and is attached to the peripheral part of the window panel by being molded thereon in situ. The molding seals the gap between the window panel and the window opening by resiliently engaging the opposing edge of the window opening. It is known in a window module for opening and closing a sunroof opening to form a molding along the edge of a window panel, providing an engagement groove extending along the length of the molding, and preparing a hollow weather strip provided with an engagement portion along a side thereof so that the weather strip may be placed along the length of the molding by engaging the engagement portion with the engagement groove (See Patent Document 1, for instance). The window module disclosed in Patent Document 1 allows the highly flexible weather strip to be attached to the peripheral part of the window panel without requiring a bonding agent.